The movie is set is Los Angeles and is a maze of interconnecting storylines, focusing on couples and singles of varying ages and how they deal with the expectations and pressure that Valentine's Day represents.

Roberts' first collaboration with Marshall in Pretty Woman 20 years ago changed her life. Arguably, if not for Marshall casting the then-unknown actress, Roberts may not have earned a permanent place on the Forbes list of highest grossing earners.

Roberts acknowledges the role Marshall has played in her life. "I owe him my entire career, even the bad ones."

Going with the Field of Dreams adage, "If you build it, they will come" evidently rings true: if you cast Roberts, other stars will jump on board.

"Garry made me do it," she smiles. "He said, 'You have to do it!'

"It was like that. He came over to my house. I fed him a nice lunch. It's not that I'm anti-romantic comedy. I like being funny, I like being romantic. It's just really challenging to find scripts that are original or interesting, particularly when you're 41. They become more challenging because the scenarios have to be more original or more interesting because you can't just be falling off chairs as amusingly. And, you get hurt when you're older."

At the centre of the meshing storylines is Ashton Kutcher, a florist with a penchant for wearing pink. "Florists are the messengers," he says. "Think about it. They deliver notes - good news or bad. They know who's married and who's being unfaithful."

He says, "I hate Valentine's Day. I can't stand it. I think that every day should be the day. You should celebrate love 364 days out of the year, and then Valentine's Day should be the day where you get to tell whoever you hate, that you can't stand them. And then on that day of hate, you would send a flower, bouquets to people you don't like with a message saying, 'I don't like you. This is why ... ' So, maybe we should only give gifts for the people we don't like this year."

Love-deprived Biel's character is a neurotic publicist who holds an annual "I Hate Valentine's Day" party. She says, "I'm not a lover or a hater of Valentines's Day."

In her personal life, she has been in a relationship with Justin Timberlake for several years. "I'm neutral. I'm not one of those extreme people who goes absolutely crazy for it, I can take it or leave it. But I love chocolate so it's a good reason to eat it," she says.

Marshall hopes the success of his past movies with Roberts will repeat itself with Valentine's Day, even though she doesn't have a lot of screen time (but of course features heavily in the trailer).

It begs the question; will there be a sequel to Pretty Woman? Roberts says, "Should I tell them, Garry? Nobody wants to see an old hooker." Maclaine replies, "Oh, I'm not so sure about that." Her droll wit clearly hasn't softened with age, referring to a litany of movies in which she played prostitutes.

Maclaine has a decent-sized role in the movie playing an ageing movie star married to the character played by Hector Elizondo (who has been gainfully employed by Marshall in 16 of his movies). She delivers some unexpected bad news for him and there's a pivotal moment in the Hollywood Forever cemetery (a hotspot where avid movie-goers watch classic films at midnight amidst celebrity graves belonging to the likes of Rudolph Valentino, Jayne Mansfield and Douglas Fairbanks jnr).

Marshall laughs: "Yes, when we did the cemetery scene, Shirley knew many of the people." Revelling in her famed knack for communicating with "the other side", Maclaine says, "Yes, I spoke to them all evening. They were keeping me warm. They were keeping me cool. It was very, very reassuring to me that nothing ever dies."

Referring to her claims of reincarnation (which includes an affair she had with Charlemagne, no less, around 800 AD), she says of her illustrious career in movies, "I like playing other people since I was so many of them. I enjoy the whole pretence of playing like I'm someone else. I don't think I'll retire. They might retire me but it won't be of my own volition."

Marshall was clever to include the storyline featuring teen heart-throbs Taylor Lautner and country pop sensation and Grammy-award winner, Taylor Swift. The onscreen couple had a short-lived relationship offscreen during the shoot.